Improvement in sawing stone



R. 'A'. T ILGHMAN.

' SAWING STONE. No.187,z39. Patented Feb.13,1e77.

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i 'LL' i UNITED STATES PATENT QFFICE.

RICHARD A. TILGHMAN, OF PHILADELPHIA, PENNSYLVANIA.

IMPROVEMENT IN SAWING STONE.

Specification forming part of Letters Patent No. 187,239, dated February I3, 1877: application led December 20, 1676.

To all whom it may concern Be it known that 1, RICHARD A. TILGHMAN, 0l' Philadelphia, Pennsylvania, have invented certain lmprovmnents in Sewing Stone, of which the following is a specification:

My invention consists in an improvement upon the process patented to B. C. 'lilghman, November 26, 1872, No. 133,501, for cutting hard substances by using metallic grains or globules in place ot' sand.

In the early applications ot' said .process it was considered to be better to use grains or globules of nearly uniform sizes during the same operation, and thatpwheu the globules became worn or broken much below their average original size the small particles became inefficient in cutting, because ot' their tendency to escape the pressure of the sawblade.

Now, I have discovered, by experiment, that in sawing stone with metallic grains or globules, I can obtain greater rapidity and economy by using, instead ot' uniform sizes, a mixture of various sizes ot' globules, keeping below that maximum size, which is governed by the nature ot' the stone and the desired smoothness of cut. The following is a method of carrying my lnvention into eliect as applied to the sawing ot' stone:

The grains or globules are to be applied to the saw in the same manner as the sand commonly used, and arefed into the saW-kerf with small streams of Water, so that a eonstunt supply ot' them will be washed down, and will be caught and rubbed between the edge ol' the saw and the stone. The grains which escape from the kerf are collected and thrown back again to feed the saw, after suitable washing, it' required, to remove the mud of the powdered stone; but the small pieces and powder of the worn and broken grains of metal should not be removed, as I find they are still useful in cutting the stone.

The explanation ot the improved results which I have obtained by the use of a mixture of grains or globules of vazious sizes I believe to be this: The Wear on the cuttingedge of' the saw-blade keeps it of a rounded section, nearly semi-cylindrical, and as the kerfor cut in the stone is always wider than the saw-blade, the globules, pressed upon by thls ro-.und edge of the moving blade, have a tendency to escape its pressure by rolling from under it to the sides of the kerf.

Now, il' the globules are all ol' about the same size, and were all under pressure simultaneously, they would escape sidewse nearly about the same time, and the result would be that the saw-blade Would then be let down to the bare stone, on which it would rub uselessly for the remainder ot its stroke.

If a mixture of globules of various sizes is used, the cutting effect would commence by the saw pressing upon the largest globules, while the smaller would lie loose on the bottom of the kerf; then, as the largest escaped sidewise, those somewhat smaller would be caught bythe saw and receive its pressure and begin to cut, and so on with the smaller sizes, successively to the end of the stroke, the result being that the saw would be less likely to reach the bare stone, and more likely to cut during the whole length ot' the stroke.

Beside this increased cutting efficiency, the use of mixed sizes ot' grains or globules has an additional economy in the cost ot' the material employed.

In the production of grains or globules by the subdivision of melted iron or steel, or their alloys, various sizes ot' grains are produced simultaneously, and these would require to be sit'ted into many different lots, it' each size was to be used separately, and t'or some of these sizes there might be but little demand; whereas, by my improvement, after separating what is too coarse land the tine dust, the entire remainder can be used together, and consequently at less cost.

I do not claim anything included or described in the patent of I5. C. 'lilghman, ot' November 26, 1872, No. 133,501; but

I claim as my invention- The use ot' a mixture ol' diierent sizes ot' grains or globules obtained from melted iron or steel, or their alloys, in the sawing' ot' stone, glass, pottery, and similar hard substances, in place ot' using` grains or' nearly uniform size in the same operation, as heretofore supposed to be preferable in practicing the said process patented to B. G. Tilghman. v

E. A. TILGHMAN. Witnesses:

B. G. TILGHMAN, J. BoNsALL TAYLOR. 

